Edit in JSFiddle

//dom ready
var cnt1 = 0;
var cnt2 = 0;
var cnt3 = 0;
Event.ready(function () {
    Event.on(document.getElementById('delegate_container1'), 'click', 'div', function (e) {
       $(document.getElementById('delegate_container1')).append('<div style="position:relative;width:200px;">div' + (cnt1++) + '</div>');
    });

   Event.on(document.getElementById('delegate_container2'), 'click', 'p', function (e) {
        $(document.getElementById('delegate_container2')).append('<p style="position:relative;width:200px;">p' + (cnt2++) + '</p>');
    });

    Event.on(document.body, 'click', function (e) {
        $(document.getElementById('delegate_container3')).append('<div style="position:relative;width:200px;">body' + (cnt3++) + '</div>');
    });
});